A range of Bessel-Thomson (BT) filters is available for standard bit rates. These filters are essential for accurate characterization of signals emerging from an optical transmission system. Connecting a BT filter between the output of the optical to electrical (O/E) converter and the scope input ensures an accurate representation of the signal that an equalized optical receiver would see, enabling the PicoScope 9221A, 9231A and PicoScope 9321 to display correct measurements.

Choosing the correct BT filter for the application is simple using the table below with common bit rates and their associated serial data or communication standard.